This invention relates to vehicle service apparatus and more particularly to measuring vehicle ride height.
The ride height of a vehicle may be defined in various ways. For example, some manufacturers specify ride height as the distance from the ground to the vehicle bumper, while others may use the distance between the center of a wheel (or some other reference point) and the vehicle body wheel arch for that wheel. No matter how defined, the ride height typically changes over time. These changes result from wear of or damage to the suspension components or incorrect adjustment, and can be evidence of serious alignment problems. Some manufacturers provide specifications for ride height which, if ignored, can result in failure to adequately diagnose and repair misalignment of the vehicle.
U.S. Pat. No. 4,977,524 to Strege et al (co-assigned with the present application) discloses an electronic measuring gauge for measuring ride height which supplies the measured ride height to a vehicle inspection/alignment system. That electronic measuring gauge was hand held by the technician/user and was connected by a separate cable to the inspection/alignment system console. The console included a computer with a memory which compared the measured ride height from the hand held measuring gauge with stored specifications for ride height.
Although the prior art ride height measuring devices worked adequately, they could be improved. Hand held measuring devices, for example, tend to be prone to human error in placement and the like. Such errors in placement with a hand held device can occur at either the upper or lower measuring point (e.g., at the wheel arch, bumper or other upper measuring point on the one hand, or at the wheel axle, ground or other lower measuring point on the other), or at both. Moreover, the prior art devices were not necessarily readily usable when other measuring equipment, such as wheel alignment sensors, were already mounted on the wheel. This could necessitate a two-step process in which the ride height measuring gauge was used first and then the wheel alignment sensor was mounted on the wheel, or vice versa.
Moreover, when the ride height is referenced to the measurement is subject to error because it depends in that case on tire pressure and/or tire size. Heretofore, apparatus for converting a ground-to-upper reference point ride height specification to a corresponding specification which does not depend upon tire pressure or tire size has not been available.